One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10)(11,15)(12,13)(14,16)(17,18)(19,21)(20,22)(23,24)(25,26,30,31)(27,28,33,32)(29,34,37,38)(35,36,40,39)(1,2)(3,6)(4,5)(7,8)(9,11,14,13)(10,15,16,12)(26,31)(27,33)(29,37)(36,39)(2,5)(6,7)(10,16)(12,15)(17,18,20,22)(19,21,23,24)(25,27,30,33)(26,32,31,28)(29,35,37,40)(34,39,38,36)(1,2)(3,6)(4,5)(7,8)(9,12)(10,11)(13,16)(14,15)(17,18)(19,21)(20,22)(23,24)(25,28,30,32)(26,33,31,27)(29,36,37,39)(34,40,38,35)(1,3,4,8)(2,6,5,7)(9,13,14,11)(10,12,16,15)(17,19,20,23)(18,21,22,24)(25,29,30,37)(26,34,31,38)(27,35,33,40)(28,36,32,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.